Composite co-structured or co-adsorbed, mineral or organic filler or pigment compounds and the use thereof

ABSTRACT

Composite compounds of co-structured or co-adsorbed organic or mineral fillers or pigments containing at least two organic or mineral fillers or pigments of a different nature and the use thereof in the paper industry for manufacturing paper, filling or coating or for any other surface treatment of the paper as well as wood or metal or plastic or cement surface treatment compounds in the fields of aqueous and non-aqueous paints and plastics materials. Coatings colors, uncoated filling compound and sheets of base paper for coating containing them.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of composite compounds ofmineral or organic fillers or pigments containing at least two mineralor organic fillers or pigments of different natures and the uses thereofin the paper industry for manufacturing paper, for filling or coatingpurposes, or for any other surface treatment of the paper, as well as inthe field of aqueous and non-aqueous paints and in the plasticsindustry.

2. Description of the Related Art

Composite pigments or fillers are commonly used these days for themanufacture of all types of paper, filling and coating or any othersurface treatment of the paper in order to improve the quality of thepaper in terms of its properties of opacity, whiteness and brightness ofthe sheets of paper, for example, or to improve the printabilitycharacteristics.

One widely used technique of producing composite pigments or fillersconsists in mixing a mineral filler, such as a natural calcium carbonatefor example, with a mineral filler such as talc (FR 2 526 061) oralternatively a mineral filler such as talc with another mineral fillersuch as calcined kaolin (EP 0 365 502).

Two other types of process are also known from the prior art forproducing composite pigments or fillers meeting the requisite criteriafor use in the paper industry.

A first category of these processes known from the prior art involvesforming networks between the pigment particles, thereby creatingnumerous internal voids which then enhance the optical properties of thepigment fillers, often measured by a light scattering coefficient S.

Accordingly, patent WO 92/08755 describes a method of forming aggregatesby flocculation and optionally by in situ precipitation of calciumcarbonate, this flocculation occurring consecutively with the ionicinteractions produced by using anionic polymers with a high molecularweight to flocculate the mineral particles to which multivalent cationssuch as the calcium ion are added on the surface.

Similarly, U.S. Pat. No. 5,449,402 discloses a product obtained by amethod of creating internal voids based on ionic or electrostaticinteractions, whilst U.S. Pat. No. 5,454,864 or U.S. Pat. No. 5,344,487or EP 0 573 150 propose a composite pigment, the preparation of which isbased on the attraction forces of ions.

These methods based on ionic attraction forces are sensitive to theionic forces at play in the formulas used for paper coating colors orfor paper filling and there is no guarantee that these pigments can beused in applications such as paper coating or paper filling.

A second category of these methods known from the prior art as a meansof producing pigments with improved optical characteristics is based onusing organic compounds of silicon (U.S. Pat. No. 4,818,294; U.S. Pat.No. 5,458,680) or chloride-based compounds (U.S. Pat. No. 4,820,554;U.S. Pat. No. 4,826,536; WO 97/24406).

Finally, a last known method of improving whiteness (WO 97/32934)consists in coating the pigment particles with another pigment particlesuch as very fine particles of precipitated calcium carbonate. However,a method of this type is not Lased on using an organic binding agentwhich creates a co-structure.

Faced with this problem of improving optical properties, such asopacity, whiteness, colouring or brightness, for example, or improvingprintability characteristics, the applicant has developed, for thepurposes of this invention, composite compounds, which are dry ornon-aqueous or aqueous, of mineral or organic fillers or pigments whichwill improve at least one of the optical properties or printabilityrequired in the various fields of application, whilst providing amacroscopically homogeneous and stable compound in spite of the ionicforces present in the known formulas, such as offset or rotogravurepaper coating colors or paper filling. Accordingly, one of theobjectives of the invention is to provide dry or non-aqueous or aqueouscomposite compounds of mineral or organic fillers or pigments containingat least two mineral or organic fillers or pigments of a physically orchemically different nature.

SUMMARY OF THE INVENTION

The composite compounds of organic or mineral fillers or pigmentsproposed by the invention and constituting one of the objects thereof,which exhibit the qualities outlined above, are characterised in thatthey contain

-   a) at least two organic or mineral fillers or pigments, at least one    of which has a surface having at least one hydrophilic site and the    other at least having a surface with at least one organophilic site-   b) at least one binding agent and in that they are co-structured or    co-adsorbed, i.e. the different mineral or organic particles exhibit    a structural cohesion imparted by creating a bond or an adhesion    between at least two particles with different surface states.

Consequently, throughout this description the words co-structure orco-structured or co-adsorbed are used by the applicant as meaning thecreation of a bond between at least two fillers or pigments of any typeby forming a structure comparable to a bond or an adhesion between thesurface of a filler or pigment having at least one hydrophilic site andthe surface of the other filler or pigment having at least oneorganophilic site using a binding agent which is an organic compound.This binder may be supported by a gas such as air or any other gas.

Furthermore, another objective of the invention is to develop stablecomposite compounds which can be transported and stored for severalweeks.

Yet another objective of the invention is to develop a compositecompound of a macroscopically homogeneous structure, this being achievedby macroscopically stable paper coating colors which contain theabove-mentioned composite aqueous compounds.

Moreover, another objective of the invention is the use of thesecomposite compounds as organic or mineral fillers or pigments for themanufacture of paper, filling and/or coating and/or any other compoundused to treat the surface of paper, as well as in the field of paintsand the field of plastics.

BRIEF DESCRIPTION OF THE DRAWINGS

Graph 1 shows the force that is necessary to be applied to each of twodisks each having a surface bonded film of printing ink on a disksubstrate in order to separate the film from the disk after printing,the printing films having the coating colors of Tests 119 and 120.

Graph 2 shows the force that is necessary to be applied to each of twodisks each having a surface bonded film of printing ink on a disksubstrate in order to separate the film from the disk after printing,the printing films having the coating colors of Tests 121 and 122.

Graph 3 shows the force that is necessary to be applied to each of twodisks each having a surface bonded film of printing ink on a disksubstrate in order to separate the film from the disk after printing,the printing films having the coating colors of Tests 123 and 124.

Graph 4 shows the force that is necessary to be applied to each of twodisks each having a surface bonded film of printing ink on a disksubstrate in order to separate the film from the disk after printing,the printing films having the coating colors of Tests 125 and 126.

Graph 5 shows the force that is necessary to be applied to each of twodisks each having a surface bonded film of printing ink on a disksubstrate in order to separate the film from the disk after printing,the printing films having the coating colors of Tests 127 and 128.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

Finally, another objective of the invention is to provide suspensionscontaining the composite compounds proposed by the invention and toprovide paper coating colors-or compounds for treating the surface ofpaper or uncoated filling compounds that will improve at least one ofthe properties, such as opacity, whiteness, brightness or printability.

It should be pointed out that the improvement made to these propertieswill depend on the field in which the skilled person wishes to adapt theproperties to suit the desired application.

These objectives are achieved by placing the surface of one of thepigments or fillers in contact with the surface of the other of thepigments or fillers in the presence of a binding agent so that thiscontact causes a structure to form, between at least two mineral ororganic particles of a different physical or chemical nature, i.e.causes a structure to form between them, at least one of them having asurface with at least one hydrophilic site and at least one of themhaving a surface with at least one organophilic site.

By mineral or organic particle having a surface with at least onehydrophilic site, the applicant means a mineral or organic particlewhich is partially or totally wettable by polar substances without theinfluence of any external component and more specifically is partiallyor totally wettable by water.

The mineral or organic particles having a surface with at least onehydrophilic site may be of very different physical or chemical natures,such as natural calcium carbonate, for example chalk, calcite, marble orany other form of natural calcium carbonate, which may be obtained froma recycling process in particular, precipitated calcium carbonate, thedolomites, crystalline or amorphous aluminium hydroxides, natural orsynthetic precipitated silicates, calcium sulphate, titanium dioxide,satin white, the wollastonites, huntite, calcined clays derived fromrecycling for example, starch or any other type of organophilic organicor mineral particles that have undergone physical processing such asCorona or chemical processing in order to produce at least onehydrophilic site.

By mineral or organic particle having a surface with at least oneorganophilic site, the applicant means a mineral or organic particlewhich is partially or totally wettable by an organic fluid or an organicsubstance, this wettability being independent of adsorption mechanismssuch as electrostatic attraction or sequestration.

By mineral or organic particle having a surface with at least oneorganophilic site, the applicant means in particular a mineral ororganic particle of very different physical or chemical natures such astalcs, micas, calcined clays or not, or zinc oxide or transparent ironpigments or colouring pigments such as phthalocyanine blue,polystyrene-based synthetic pigments, urea-formol resins, carbon black,cellulose fibres and flours or any other type of hydrophilic mineral ororganic particles but which, after chemical or physical processing, haveat least one organophilic site, i.e. are wettable by an organic fluid oran organic substance.

It should be pointed out that the quantities and ratios by dry weight ofthe various fillers or pigments making up the composite compoundsproposed by the invention vary from 0.1% to 99.9% depending on thenature of the different pigments or fillers, and preferably from 25% to95% by dry weight, relative to the total dry weight of the fillers orpigments, of mineral or organic fillers or pigments having a surfacewith at least one hydrophilic site and preferably between 75% and 5% bydry weight, relative to the total dry weight of the fillers or pigments,of mineral or organic fillers or pigments having a surface with at leastone organophilic site.

The creation of a bond or a co-structure can be seen in the rheologicalbehaviour of the composite compounds and by the properties ofhomogeneity in paper coating colors or in the printability of the paper.

It also increases the opacity of sheets of wood free paper filled at arate of 75.5 g/m² with the composite compounds of the invention. Thisopacity is measured in compliance with the DIN 53146 standard using anElrepho 2000 spectrophotometer made by Datacolor AG (Switzerland).

Accordingly, the composite compounds of mineral or organic fillers orpigments proposed by the invention are characterised in that they areco-structured or co-adsorbed, i.e. they have a high yield stress, asdetermined by a Stress Tech® machine, namely higher than and preferablyat least four times higher than that of the standard mixture ofcorresponding fillers or pigments.

The composite compounds of mineral or organic fillers or pigmentsproposed by the invention are also characterised in that the differentmineral or organic particles exhibit a cohesion which reflects themacroscopic homogeneity of the suspension of the composite compoundand/or coating color containing the composite compound. This macroscopichomogeneity is expressed by measuring the content of one of the pigmentsor fillers at two different points of the suspension or of the coatingcolor after it has been left to rest for several hours or several days.

Furthermore, the composite compounds of mineral or organic fillers orpigments proposed by the invention are characterised in that theycontain at least one binding agent. This binding agent is an organiccompound, which might be supported by a gas such as air or any othergas. This binding agent, an organic compound, must be partially ortotally wettable by the surfaces of the pigments or fillers with whichit is placed in contact. By preference, this binding agent is selectedfrom among the acrylic or vinyl polymers and/or copolymers orpolycondensates or polyaddition products such as the polymers orcopolymers for example, in their totally acid state or partiallyneutralised or totally neutralised by neutralising agents containingmonovalent or polyvalent cations or mixtures thereof, by one at least ofthe monomers such as acrylic and/or methacrylic, itaconic, crotonic,fumaric acid, maleic anhydride or isocrotonic, aconitic, mesaconic,sinapic, undecylenic, angelic acid and/or the respective esters thereof,acrylamido methyl propane sulphonic acid, acrolein, acrylamide and/ormethacrylamide, methacrylamido propyl trimethyl ammonium chloride orsulphate, methacrylate of trimethyl ammonium ethyl chloride or sulphate,as well as their acrylate and acrylamide counterparts, quatemised ornot, and/or dimethyldiallyl chloride, vinylpyrrolidone or a bindingagent selected from among the linear or branched fatty acids or thelinear or branched fatty alcohols or the linear or branched or cyclicfatty amines, saturated or not, or selected from among the quaternarysalts preferably with linear or branched fatty chains of vegetableorigin or not.

This binding agent may also be selected from among at least one of theabove-mentioned monomers or mixtures thereof in the form of the monomeror monomers itself/themselves, polymerised in the presence of at leastone of the mineral or organic particles.

Furthermore, it should be noted that optimisation of the molecularweight of the binding agent will depend on its chemical nature.

For the purposes of the invention, the quantity of binding agent used inthe composite compound is from 0.01% to 10%, preferably from 0.10% to1.5% by dry weight relative to the total dry weight of the fillers orpigments.

The composite compounds proposed by the invention may optionally bedispersed in water, in water-solvent mixtures or in other solvents usingone or more dispersing agents known to the person skilled in the art,amongst others those described in patents EP 0 100 947, EP 0 542 643 orEP 0 542 644.

It is also important to note that the co-structured composite compoundsproposed by the invention are compatible with other aqueous mineral ororganic filler compounds, i.e. they form a stable and homogeneousmixture when they are simply mixed with these other suspensions, whereasit would be impossible to produce a homogeneous suspension if aco-structured composite compound as proposed by the invention were notused.

The paper coating colors and/or paper surface treatment compounds aswell as wood or metal or plastic or cement surface treatmentcompounds-and/or aqueous or non-aqueous paint compositions proposed bythe invention are prepared in a manner known to the person skilled inthe art by mixing in water the dry or non-aqueous or aqueous mineral ororganic composite compounds of fillers or pigments proposed by theinvention and one or more binders of natural or synthetic origin such asstarch, carboxymethyl cellulose, the polyvinyl alcohols, for example, orlatex or polymeric dispersions of the styrene-butadiene orstyrene-acrylate type or acrylic or vinyl or other polymericdispersions.

In a known manner, the paper coating colors and/or paper surfacetreatment compounds as well as wood or metal or plastic or cementsurface treatment compounds and/or aqueous or non-aqueous paintcompositions may also contain the usual additives such as rheologymodifiers, organic fillers, anti-foaming agents, optical brighteners,biocide agents, lubricants, alkaline hydroxides, colourings and others.

In addition, the aqueous suspensions containing the composite compounds,the paper coating colors and/or the paper surface-treatment compounds aswell as wood or metal or plastic or cement surface treatment compoundsand/or aqueous or non-aqueous paint compositions or the uncoated fillingcompositions proposed by the invention are characterised in that theycontain dry or non-aqueous or aqueous composite compounds as proposed bythe invention.

The aqueous suspensions containing the composite compounds, the papercoating colors and/or the paper surface-treatment compounds as well aswood or metal or plastic or cement surface treatment compounds and/oraqueous paint or non-aqueous compositions as proposed by the inventionare also characterised in that they are macroscopically homogeneous.

This macroscopic homogeneity is determined by measuring the quantity ofone of the fillers at the surface and the base of the flask containingthe coating color diluted 40% or 20% with dry substance.

A comparison of this quantity of one of the fillers at the two “top” and“bottom” points of the compound proposed by the invention with thequantity of one of the fillers at these two “top” and “bottom” points ofthe standard mixture will demonstrate the fact that there is virtuallyno migration of one of the fillers to a preferred part of the compoundof the invention, contrary to the situation that would arise with astandard mixture.

This macroscopic homogeneity of the composite compounds of the inventionproduces improved homogeneity in the sheet of paper due to a more evenretention and distribution.

Moreover, the aqueous suspensions containing the composite compounds ofthe invention, the paper coating colors of the invention or the papersurface-treatment compounds of the invention are characterised in thatthe yield stress, as determined by a Stress Tech® machine, is higherthan and preferably at least four times higher than the correspondingstandard mixtures of fillers or pigments.

Furthermore, the aqueous suspensions of the invention or the coatingcolors of the invention or the paper surface-treatment compounds of theinvention or the uncoated filling compounds of the invention will alsoexhibit an improvement in at least one of the optical properties such asopacity or whiteness or brightness or in the printability or printdensity properties.

Likewise, the aqueous or non-aqueous paint compositions containing thecomposite compounds of the invention have the advantage of an increasedopacity.

Accordingly, by preference, the aqueous suspensions containing thecomposite compounds of the invention or the coating colors of theinvention or the paper surface-treatment compounds of the invention aswell as wood or metal or plastic or cement surface treatment compoundsand/or aqueous or non-aqueous paint compositions are characterised inthat they have a higher light scattering coefficient S than that of thecorresponding standard mixtures.

The uncoated filling compounds proposed by the invention are preferablycharacterised in that they exhibit a higher opacity, determined incompliance with the DIN 53416 standard, than that of the correspondingstandard mixtures.

Similarly, by preference, the aqueous suspensions containing thecomposite compounds of the invention or the coating colors of theinvention or the paper surface-treatment compound of the invention orthe uncoated filling compounds of the invention are characterised inthat they have a higher whiteness, determined in compliance with theTAPPI T452 ISO 2470 standard, than that of the corresponding standardmixtures.

By preference, the coating colors or paper surface-treatment compoundsproposed by the invention are characterised in that they exhibit ahigher TAPPI 75° brightness according to Lehmann than that of a coatingcolor containing standard suspensions of corresponding mixtures.

Finally, and by preference, the coating colors or papersurface-treatment compounds or uncoated filling compounds proposed bythe invention are characterised in that the curve, plotted on the basisof the ISIT printability test, the conducting of which will be explainedin example 9, representing the ink tack force as a function of time,exhibits less marked rising and falling slopes and a higher maximumvalue than coating colors or paper surface-treatment compounds oruncoated filling compounds containing standard suspensions ofcorresponding mixtures.

Furthermore, sheets of paper which contain in the mass the compositecompounds proposed by the invention are characterised in that theyexhibit a higher whiteness, determined in compliance with the TAPPI T452ISO 2470 standard, than sheets of paper containing in the mass standardsuspensions of mixtures of corresponding fillers or pigments and in thatthey exhibit a higher opacity, measured in compliance with the DIN 53146standard, than sheets of paper containing standard suspensions ofmixtures of corresponding fillers or pigments.

The scope and interest of the invention will be more readily understoodfrom the examples set out below, which are not intended to berestrictive, particularly in terms of the order in which the variousconstituents of the composite compounds are added.

Example 1

This example relates to the preparation of composite compoundscontaining different pigments or fillers.

The specific viscosities mentioned in all the examples are determined bythe method defined in EP 0 542 643.

Test N^(o) 1:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 72% aqueous suspension of a Norwegian marble witha grain size equivalent to one in which 75% of the particles are of adiameter of less than 1 Eun as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 250 grams dry weight of an aqueoussuspension of Finnish talc with a grain size equivalent to one in which45% of the particles are of a diameter of less than 2Eun as measured onthe Sedigraph 5100 containing 0.08% by dry weight of soda, 1.4% by dryweight of an alkylene polyoxide and 0.15% by dry weight of a sodiumpolyacrylate with a specific viscosity of 0.4 in order to produce anaqueous suspension with a 70% concentration of a marble-talc mixture.

Test N^(o) 2:

For this test, illustrating the invention, the co-structured aqueouscompound of the invention is prepared by adding in a mixer and underagitation:

-   -   750 grams dry of Norwegian marble having a grain size such that        75% of the particles are of a diameter of less than 1 μm as        measured on the Sedigraph 5100,    -   250 grams dry weight of a talc from Finland with a grain size        such that 45% of the particles are of a diameter of less than 2        μm as measured on the Sedigraph 5100,    -   5 grams dry weight of an acrylic copolymer binding agent of a        monomer composition comprising 90% by weight of acrylic acid and        10% by weight of tristyrylphenol methacrylate with 25 moles of        ethylene oxide,    -   the quantity of water needed to make up the co-structured        aqueous compound of the invention to a 65% concentration of dry        substance.

After agitating for 30 minutes and after formation of the co-structurebetween the grains of marble and talc with the aid of the binding agent,5.2 grams dry weight of a dispersing agent of the prior art, namely apolyacrylate partially neutralised with soda and having a specificviscosity of 0.5, are added to the compound of the invention, thebalance being added in the form of soda and water necessary to producean aqueous suspension of the composite compound of the invention with aconcentration of dry substance equal to 59.1% with a pH of between 9 and10.

Test N^(o) 3:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 72% aqueous suspension of Champagne chalk with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 0.80% by dry weight of a sodium polyacrylate with a specificviscosity equal to 0.5 with 250 grams dry weight of an aqueoussuspension of a Finnish talc with a grain size equivalent to one inwhich 45% of the particles are of a diameter of less than 2 μm asmeasured on the Sedigraph 5100 containing 0.08% by dry weight of soda,1.4% by dry weight of an alkylene polyoxide and 0.15% by dry weight of asodium polyacrylate with a specific viscosity of 0.4 in order to producean aqueous suspension with a 62.1% concentration of achalk-talc-mixture.

Test N^(o) 4:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment as test N^(o) 2 replacing the marble withChampagne chalk of the same grain size.

This produces an aqueous suspension of the co-structured compositecompound of the invention (75% by dry weight of chalk-25% by dry weightof talc) having a 57% concentration of dry substance.

Test N^(o) 5:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 51% aqueous suspension of precipitated calciumcarbonate with a grain size equivalent to one in which 60% of theparticles are of a diameter of less than 2 μm as measured on theSedigraph 5100 and dispersed with 0.3% by dry weight of a sodiumpolyacrylate with a specific viscosity equal to 0.7 with 250 grams dryweight of an aqueous suspension of a Finnish talc with a grain sizeequivalent to one in which 45% of the particles are of a diameter ofless than 2 μm as measured on the Sedigraph 5100 containing 0.08% by dryweight of soda, 1.4% by dry weight of an alkylene polyoxide and 0.15% bydry weight of a sodium polyacrylate with a specific viscosity of 0.4 inorder to produce an aqueous suspension with a 54.5% concentration of aprecipitated calcium carbonate-talc mixture.

Test N^(o) 6:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment as test N^(o) 2 replacing the marble withprecipitated calcium carbonate with a grain size equivalent to one inwhich 60% of the particles are of a diameter of less than 2 μm.

This produces an aqueous suspension of the co-structured compositecompound of the invention (75% by dry weight of precipitated calciumcarbonate-25% by dry weight of talc) having a 58% concentration of drysubstance.

Test N^(o) 7:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1.00% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 250 grams dry weight of an aqueoussuspension of an Austrian mica with a grain size equivalent to one inwhich 18% of the particles are of a diameter of less than 1 μm asmeasured on the Sedigraph 5100 containing 0.25% by dry weight of asodium polyacrylate with a specific viscosity of 0.4 in order to producean aqueous suspension with a 68.6% concentration of a marble-micamixture.

Test N^(o) 8:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment as test N^(o) _(—)2 replacing the talc withAustrian mica with a grain size equivalent to one in which 18% of theparticles are of a diameter of less than 1 μm.

This produces an aqueous suspension of the co-structured compositecompound of the invention (75% by dry weight of marble-25% by dry weightof mica) having a 61.3% concentration of dry substance.

Test N^(o) 9:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 250 grams dry weight of an aqueoussuspension of an English kaolin with a grain size equivalent to one inwhich 64% of the particles are of a diameter of less than 1 μm asmeasured on the Sedigraph 5100 containing 0.2% by dry weight of a sodiumpolyacrylate with a specific viscosity of 0.4 in order to produce anaqueous suspension with a 70.2% concentration of a marble-kaolinmixture.

Test N^(o) 10:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment as test N^(o) 2 replacing the talc withEnglish kaolin having a grain size equivalent to one in which 64% of theparticles are of a diameter of less than 1 μm as measured by theSedigraph 5100.

This produces an aqueous suspension of the co-structured compositecompound of the invention (75% by dry weight of marble-25% by dry weightof kaolin) having a 62.1% concentration of dry substance.

Test N^(o) 11:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 250 grams dry weight of an aqueoussuspension of a titanium dioxide of the rutile type with a grain sizeequivalent to one in which 86% of the particles are of a diameter ofless than 1 μm as measured on the Sedigraph 5100 containing 0.32% by dryweight of a sodium polyacrylate with a specific viscosity of 0.4 inorder to produce an aqueous suspension with a 71.5% concentration of amarble-titanium dioxide mixture.

Test N^(o) 12:

For this test, illustrating the invention, the co-structured compound isprepared in the same manner and using the same equipment as test N^(o) 2replacing the talc with titanium dioxide of the rutile type having agrain size equivalent to one in which 86% of the particles are of adiameter of less than 1 μm.

After the co-structure has formed between the grains of marble andtitanium dioxide with the aid of a binding agent, 0.15% by dry weight ofa dispersing agent known from the prior art is added, namely a sodiumpolyacrylate with a specific viscosity of 0.5.

This produces an aqueous suspension of the co-structured compositecompound of the invention (75% by dry weight of marble-25% by dry weightof titanium dioxide) having a 58.8% concentration of dry substance.

Test N^(o) 13:

This test, illustrating the prior art, is a standard mixture of 750grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with:

-   -   125 grams dry weight of an aqueous suspension of English kaolin        with a grain size equivalent to one in which 64% of the        particles are of a diameter of less than 1 μm as measured on the        Sedigraph 5100 and containing 0.3% by dry weight of a sodium        polyacrylate with a specific viscosity of 0.4    -   125 grams dry weight of an aqueous suspension of Finnish talc        with a grain size equivalent to one in which 45% of the        particles are of a diameter of less than 2 μm as measured on the        Sedigraph 5100 and containing 0.08% by dry weight of soda, 1.4%        by dry weight of an alkylene polyoxide and 0.15% by dry weight        of a sodium polyacrylate with a specific viscosity of 0.4 in        order to produce an aqueous suspension with a 70.2%        concentration of dry substance in a marble-kaolin-talc mixture.

Test N^(o) 14:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment as test N^(o) 2 replacing half of the talcwith English kaolin having a grain size equivalent to one in which 64%of the particles are of a diameter of less than 1 μm as measured by theSedigraph 5100.

This produces an aqueous suspension of the co-structured compositecompound of the invention (75% by dry weight of marble-12.5% by dryweight of kaolin-12.5% by dry weight of talc) having a 60.0%concentration of dry substance.

Test N^(o) 15:

This test, illustrating the prior art, is a standard mixture of 800grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 200 grams dry weight of an aqueoussuspension of crystalline aluminium hydroxide with a grain sizeequivalent to one in which 72% of the particles are of a diameter ofless than 2 μm as measured on the Sedigraph 5100 and containing 0.3% bydry weight of a sodium polyacrylate with a specific viscosity of 0.7 inorder to produce an aqueous suspension with a 70.9% concentration of drysubstance in a marble-aluminium hydroxide mixture.

Test N^(o) 16:

For this test, illustrating the invention, the co-structured aqueouscompound proposed by the invention is prepared by introducing into amixer under agitation:

-   -   800 grains dry weight of a Norwegian marble with a grain size        such that 75% of the particles are of a diameter of less than 1        μm as measured on the Sedigraph 5100,    -   200 grams dry weight of crystalline aluminium hydroxide with a        grain size such that 72% of the particles are of a diameter of        less than 2 μm as measured on the Sedigraph,    -   4 grams dry weight of an acrylic copolymer binding agent of a        monomer composition comprising 90% by dry weight of acrylic acid        and 10% by dry weight of tristyrylphenol methacrylate with 25        moles of ethylene oxide,    -   the quantity is made up with the water necessary to produce a        co-structured aqueous compound of the invention with a 65%        concentration of dry substance.

After 30 minutes of agitation and once the co-structure has formedbetween the grains of marble and aluminium hydroxide with the aid of thebinding agent, 5.6 grams by dry weight of a dispersing agent known fromthe prior art are added to the compound of the invention, namely apolyacrylate partially neutralised with soda and of a specific viscosityof 0.5, as well as the soda and water required to obtain an aqueoussuspension of the composite compound of the invention having aconcentration of dry substance equal to 60.3% and with a pH value ofbetween 9 and 10.

Test N^(o) 17:

This test, illustrating the prior art, is a standard mixture of 800grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 200 grams dry weight of an aqueoussuspension of a urea-formol condensate with a specific surface areaequal to 17 m²/g as measured by the BET method (DIN 66132) andcontaining 0.5% by dry weight of a sodium polyacrylate with a specificviscosity of 0.7 in order to produce an aqueous suspension with a 45.1%concentration of dry substance in a marble-urea-formol condensatemixture.

Test N^(o) 18:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment in all respects as test N^(o) 16 replacingthe aluminium hydroxide with a urea-formol condensate having a specificsurface area of 17 M²/g as measured by the BET method (DIN 66132).

This produces an aqueous suspension of the co-structured compositecompound of the invention (80% by dry weight of marble-20% by dry weightof a urea-formol condensate) having a 51.2% concentration of drysubstance.

Test N^(o) 19:

This test, illustrating the prior art, is a standard mixture of 800grams dry weight of a 72% aqueous suspension of Norwegian marble with agrain size equivalent to one in which 75% of the particles are of adiameter of less than 1 μm as measured on the Sedigraph 5100 andcontaining 1% by dry weight of an acrylic copolymer with a specificviscosity equal to 0.8 with 200 grams dry weight of an aqueoussuspension of bleached cellulose with a grain size equivalent to one inwhich 99% of the particles are of a diameter of less than 75 μm asmeasured by an airflow sieve of the Alpine LS 200 type and containing0.5% by dry weight of a sodium polyacrylate with a specific viscosity of0.7 in order to produce an aqueous suspension with a 44.8% concentrationof dry substance in a marble-bleached cellulose mixture.

Test N^(o) 20:

This test, illustrating the invention, is conducted in the same mannerand using the same equipment in all respects as test N^(o) 16 replacingthe aluminium hydroxide with bleached cellulose with a grain sizeequivalent to on in which 99% of the particles are of a diameter of lessthan 75 μm as measured by an airflow sieve of the Alpine LS 200 type.

This produces an aqueous suspension of the co-structured compositecompound of the invention (80% by dry weight of marble-20% by dry weightof bleached cellulose) having a 46.9% concentration of dry substance.

Test N^(o) 21:

This test, illustrating the prior art, is a standard mixture of 500grams dry weight of a Champagne chalk with a grain size equivalent toone in which 45% of the particles are of a diameter of less than 2 μm asmeasured on the Sedigraph 5100 with 500 grams of an Australian talc witha grain size equivalent to one in which 25% of the particles are of adiameter of less than 2 μm as measured by the Sedigraph 5100 to producea powdered chalk-talc mixture with a 100% concentration of drysubstance.

Test N^(o) 22:

For this test, illustrating the invention, the co-structured compound isprepared in a powdered form as proposed by the invention, by introducinginto a mixer under agitation:

-   -   500 grams dry weight of a Champagne chalk of a grain size such        that 45% of the particles are of a diameter of less than 2 μm as        measured on the Sedigraph 5100,    -   500 grams dry weight of a talc from Australia of a grain size        such that 25% of the particles are of a diameter of less than 2        μm as measured on the Sedigraph 5100,    -   10 grams dry weight of an acrylic copolymer binding agent of a        monomer composition comprising 90% by dry weight of acrylic acid        and 10% by dry weight of tristyrylphenol methacrylate with 25        moles of ethylene oxide.

Test N^(o) 23:

This test, illustrating the prior art, is a simple mixture of 900 gramsdry weight of an aqueous suspension of a Finnish talc with a grain sizeequivalent to one in which 45% of the particles are of a diameter ofless than 2 Fun as measured on the Sedigraph 5100 and containing 0.08%by dry weight of soda, 1.4% by dry weight of an alkylene polyoxide and0.15% by dry weight of a sodium polyacrylate with a specific viscosityof 0.4 with 100 grams dry weight of an American kaolin with a grain sizeequivalent to one in which 91% of the particles are of a diameter ofless than 0.5 μm as measured by the Sedigraph 5100 to produce an aqueoussuspension with a 67.8% concentration of a talc-kaolin mixture.

Example 2

This example illustrates the preparation of composite compounds asproposed by the invention using various ratios of pigments or fillers.

To this end, the composite compounds proposed by the invention areprepared using the same method and the same equipment as in test N^(o) 2with the exception of the quantity of water, which is added all at once,to produce the final concentration of dry substance and comprising:

Test N^(o) 24:

-   -   95% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   5% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.1% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 59.8% concentration of cry        substance using water and 0.67% by dry weight, relative to the        total dry weight of fillers, of a polyacrylate partially        neutralised with soda and having a specific viscosity of 0.54.

Test N^(o) 25:

-   -   90% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   10% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.2% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 59.8% concentration of dry        substance using water and 0.63% by dry weight, relative to the        total dry weight of fillers, of a polyacrylate partially        neutralised with soda and having a specific viscosity of 0.54.

Test N^(o) 26:

-   -   85% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        75% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   15% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.3% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 34.0% concentration of dry        substance using water and 0.78% by dry weight, relative to the        total dry weight of fillers, of a sodium polyacrylate having a        specific viscosity of 0.54.

Test N^(o) 27:

-   -   80% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   20% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.4% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 59.7% concentration of dry        substance using water and 0.56% by dry weight, relative to the        total dry weight of fillers, of a polyacrylate partially        neutralised with soda and having a specific viscosity of 0.54.

Test N^(o) 28:

70% by dry weight, relative to the total dry weight of fillers, ofNorwegian marble with a grain size equivalent to one in which 75% of theparticles are of a diameter of less than 1 μm as measured with theSedigraph 5100

-   -   30% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.6% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension with a 37.5% concentration of        dry substance using water and 0.64% by dry weight, relative to        the total dry weight of fillers, of a sodium polyacrylate having        a specific viscosity of 0.54.

Test N^(o) 29:

-   -   70% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   30% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.6% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 58.0% concentration of dry        substance using water and 0.49% by dry weight, relative to the        total dry weight of fillers, of a partially neutralised sodium        polyacrylate having a specific viscosity of 0.5.

Test N^(o) 30:

This test, illustrating the prior art, is a simple mixture of 700 gramsdry weight of an aqueous suspension of a Norwegian marble with a grainsize equivalent to one in which 62% of the particles are of a diameterof less than 1 μm as measured on the Sedigraph 5100 and containing 1% bydry weight of a sodium polyacrylate with a specific viscosity of 0.7with 300 grams dry weight of an aqueous suspension of Finnish talc witha grain size equivalent to one in which 45% of the particles are of adiameter of less than 2 μm as measured by the Sedigraph 5100 containing0.08% by dry weight of soda, 1.4% by dry weight of an alkylene polyoxideand 0.15% by dry weight of a sodium polyacrylate with a specificviscosity of 0.4 to produce an aqueous suspension with a 66.4%concentration of a marble-talc mixture.

Test N^(o) 31:

For this test, illustrating the invention, the following compositecompound proposed by the invention is prepared, using the same equipmentand the same manner as test N^(o) 29.

-   -   50% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   50% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   1.0% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        acrylic acid and 10% by weight tristyrylphenol methacrylate with        25 moles of ethylene oxide    -   and placed in aqueous suspension at a 59.8% concentration of dry        substance using water and 0.7% by dry weight, relative to the        total dry weight of fillers, of a partially neutralised sodium        polyacrylate having a specific viscosity of 0.5 and 0.2% by dry        weight, relative to the total dry weight of fillers, of a        naphthalene sulphonic acid condensate.

Test N^(o) 32:

As in the previous test, the following composite compound according tothe invention is prepared.

-   -   25% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   75% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   1.5% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 56.6% concentration of dry        substance using water and 0.63% by dry weight, relative to the        total dry weight of fillers, of a partially neutralised sodium        polyacrylate having a specific viscosity of 0.5 and 0.05% by dry        weight, relative to the total dry weight of fillers, of a        naphthalene-sulphonate acid condensate.

Example 3

This example illustrates the preparation of composite compounds of theinvention using different quantities of binding agent for a same pigmentor filler composition.

To this end, the composite compounds proposed by the invention areprepared using the same method and the same equipment as in example 2and comprise:

-   -   75% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        62% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   25% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   and, as a binder, a same binding agent in different quantities.

These different quantities of binding agent tested, acrylic copolymer ofa monomer composition comprising 90% by weight of acrylic acid and 10%by weight of tristyrylphenol methacrylate with 25 moles of ethyleneoxide, are as follows:

Test N^(o) 33:

0.13% of binding agent by dry weight relative to the total dry weight offillers.

An aqueous suspension with a 36.8% concentration of dry substances isformed using water and 0.69% by dry weight, relative to the total dryweight of fillers, of a sodium polyacrylate with a specific viscosity of0.54.

Test N^(o) 34:

0.25% of binding agent by dry weight relative to the total dry weight offillers.

An aqueous suspension with a 36.6% concentration of dry substances isformed using water and 0.69% by dry weight, relative to the total dryweight of fillers, of a sodium polyacrylate with a specific viscosity of0.54.

Test N^(o) 35:

0.38% of binding agent by dry weight relative to the total dry weight offillers.

An aqueous suspension with a 36.7% concentration of dry substances isformed using water and 0.69% by dry weight, relative to the total dryweight of fillers, of a sodium polyacrylate with a specific viscosity of0.54.

Test N^(o) 36:

1.25% of binding agent by dry weight relative to the total dry weight offillers.

An aqueous suspension with a 36.1% concentration of dry substances isformed using water and 0.69% by dry weight, relative to the total dryweight of fillers, of a sodium polyacrylate with a specific viscosity of0.54.

Example 4

This example illustrates the preparation of composite compounds asproposed by the invention using fillers or pigments of different grainsizes.

To this end, the composite compounds proposed by the invention areprepared by the same method and using the same equipment as in example 2and comprise:

Test N^(o) 37:

75% by dry weight, relative to the total dry weight of fillers, ofNorwegian marble with a grain size equivalent to one in which 62% of theparticles are of a diameter of less than 1 μm as measured with theSedigraph 5100

-   -   25% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.5% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 36.5% concentration of dry        substance using water and 0.69% by dry weight, relative to the        total dry weight of fillers, of a sodium polyacrylate having a        specific viscosity of 0.54.

Test N^(o) 38:

-   -   75% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        35% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   25% by dry weight, relative to the total dry weight of fillers,        of Finnish talc with a grain size equivalent to one in which 45%        of the particles are of a diameter of less than 2 μm as measured        by the Sedigraph 5100    -   0.5% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 36.4% concentration of dry        substance using water and 0.69% by dry weight, relative to the        total dry weight of fillers, of a sodium polyacrylate having a        specific viscosity of 0.54.

Test N^(o) 39:

-   -   75% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        75% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   25% by dry weight, relative to the total dry weight of fillers,        of Australian talc with a grain size equivalent to one in which        25% of the particles are of a diameter of less than 2 μm as        measured by the Sedigraph 5100    -   0.5% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 35.4% concentration of dry        substance using water and 0.52% by dry weight, relative to the        total dry weight of fillers, of a polyacrylate partially        neutralised by soda, having a specific viscosity of 0.5.

Test N^(o) 40:

-   -   75% by dry weight, relative to the total dry weight of fillers,        of Norwegian marble with a grain size equivalent to one in which        75% of the particles are of a diameter of less than 1 μm as        measured with the Sedigraph 5100    -   25% by dry weight, relative to the total dry weight of fillers,        of American talc with a grain size equivalent to one in which        35% of the particles are of a diameter of less than 2 μm as        measured by the Sedigraph 5100    -   0.5% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 36.1% concentration of dry        substance using water and 0.52% by dry weight, relative to the        total dry weigh of fillers, of a polyacrylate partially        neutralised by soda having a specific viscosity of 0.5.

Test N^(o) 41:

-   -   50% by dry weight; relative to the total dry weight of fillers,        of Champagne chalk with a grain size equivalent to one in which        36% of the particles are of a diameter of less than 2 μm as        measured with the Sedigraph 5100    -   50% by dry weight, relative to the total dry weight of fillers,        of Australian talc with a grain size equivalent to one in which        25% of the particles are of a diameter of less than 2 μm as        measured by the Sedigraph 5100    -   2% by dry weight, relative to the total dry weight of fillers,        of an acrylic copolymer binding agent comprising 90% by weight        of acrylic acid and 10% by weight of tristyrylphenol        methacrylate with 25 moles of ethylene oxide    -   and placed in aqueous suspension at a 59% concentration of dry        substance using water and 0.35% by dry weight, relative to the        total dry weight of fillers, of a polyacrylate partially        neutralised by soda having a specific viscosity of 0.5.

Test N^(o) 42:

This test is conducted as a comparison with the preceding test andillustrates the preparation of an aqueous suspension known from theprior art using a standard mixture of

-   -   50% by dry weight, relative to the total dry weight of fillers,        of Champagne chalk with a grain size equivalent to one in which        36% of the particles are of a diameter of Hess than 2 μm as        measured with the Sedigraph 5100 and containing 0.07% by dry        weight of a sodium polyacrylate with a specific viscosity of 0.7    -   50% by dry weight, relative to the total dry weight of fillers,        of an aqueous suspension of Australian talc with a grain size        equivalent to one in which 25% of the particles are of a        diameter of less than 2 Nm as measured by the Sedigraph 5100        containing 0.08% by dry weight of soda, 1.4% by dry weight of an        alkylene polyoxide and 0.15% by dry weight of a sodium        polyacrylate with a specific viscosity of 0.4    -   to produce an aqueous suspension with a 71.7% concentration of        dry substance of a chalk-talc mixture.

Example 5

This example relates to the use of different binding agents.

To this end, the composite compounds proposed by the invention are madeusing the same method and the same equipment as in test N^(o) 2, usingas fillers 75% by dry weight, relative to the total dry weight offillers, of Norwegian' marble with a grain size equivalent to one inwhich 75% of the particles are of a diameter of less than lam asmeasured by the Sedigraph 5100 and 25% dry weight, relative to the totaldry weight of fillers, of Finnish talc with a grain size equivalent toone in which 45% of the particles are of a diameter of less than 2 μm asmeasured by the Sedigraph 5100 and, as a binder, different quantities ofthe following different binding agents:

Test N^(o) 43:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a polyacrylic acid with a specific viscosity of1.78.

An aqueous suspension with a 59.7% concentration of dry substances isformed using water and 0.52% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 44:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a polyacrylic acid with a specific viscosity of1.55.

An aqueous suspension with a 60.4% concentration of dry substances isformed using water and 0.52% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 45:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a polyacrylic acid with a specific viscosity of0.95.

An aqueous suspension with a 59.8% concentration of dry substances isformed using water and 0.52% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 46:

0.5% by dry weight, relative to the total dry weight of fillers, of-a‘binding agent which is an acid polyacrylate, 10% neutralised by soda,having a specific viscosity of 5.00.

An aqueous suspension with a 59.9% concentration of dry substances isformed using water and 0.52% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 47:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a homopolymer of the methacrylate ofketostearylic alcohol.

An aqueous suspension with a 59.2% concentration of dry substances isformed using water and 0.45% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 48:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a copolymer comprising 98% by weight ofmethacrylic acid and 2% by weight of ketostearylic alcohol methacrylate.

An aqueous suspension with a 59.7% concentration of dry substances isformed using water and 0.52% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 49:

0.025% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a quaternary ammonium chloride having the formula

where R₁=methyl radical

R₂═R₃=lauryl radical

R₄=benzyl radical.

An aqueous suspension with a 59.3% concentration of dry substances isformed using water and 0.52% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 50:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a linear alcohol having 12 carbon atoms.

An aqueous suspension with a 55.0% concentration of dry substances informed using water and 0.75% by dry weight, relative to the total dryweight of fillers, of a polyacrylate partially neutralised with sodahaving a specific viscosity of 0.5.

Test N^(o) 51:

0.5% by dry weight, relative to the total dry weight of fillers, of abinding agent which is a linear alcohol having 18 carbon atoms.

An aqueous suspension with a 55.1% concentration of dry substances isformed using water and 0.38% by dry weight, relative to the total dryweight of fillers, of a zodium polyacrylate having a specific viscosityof 0.54.

Test N^(o) 52:

For this test, illustrating the invention, the aqueous co-structuredcompound proposed by the invention is prepared by introducing into amixer under agitation 250 grams dry weight of a Finnish talc of a grainsize such that 45% of the particles are of a diameter of less than 2 μmas measured on the Sedigraph 5100, 5 grams dry weight of mixture ofmonomers comprising 90% by weight of acrylic acid and 10% by weight oftristyrylphenol methacrylate with 25 moles of ethylene oxide, 115 gramsof isopropanol as well as the quantity of water needed to make up anaqueous composition with a 30% concentration of dry substance.

After 30 minutes of agitation, the mixture of monomers is polymerised,using known processes of radical polymerisation in a hydro-alcoholicmedium.

Once the polymerisation is complete and the isopropanol has been removedby distillation, 750 grams dry weight of Norwegian marble are added,having a grain size such that 75% of the particles are of a diameterless than 1 μm as measured by the Sedigraph 5100.

Once the co-structure has formed between the grains of talc and marbleafter 30 minutes of agitation, 7 grams by dry weight of a dispersingagent, namely a polyacrylic acid with a specific viscosity of 0.53, areadded to obtain an aqueous suspension of the composite compound of theinvention having a concentration of dry substance equal to 36.4%.

Test N^(o) 53:

This test, illustrating the invention, using the same method and thesame equipment as the preceding test, is conducted with 250 grams dryweight of a Finnish talc of a grain size such that 45% of the particlesare of a diameter of less than 2 μm as measured on the Sedigraph 5100, 5grams dry weight of a mixture of monomers comprising 90% by weight ofacrylic acid and 10% by weight of tristyrylphenol methacrylate with 25moles of ethylene oxide, to which are added 5 grams by dry weight of acopolymer comprising 90% by dry weight of acrylic acid and 10% by dryweight of tristyrylphenol methacrylate with 25 moles of ethylene oxide,115 grams of isopropanol as well as the quantity of water needed to makeup an aqueous composition with a 30% concentration of dry substance.

After 30 minutes of agitation, the mixture of monomers is polymerised,using known processes of radical polymerisation in a hydroalcoholicmedium.

Once the polymerisation is complete and the isopropanol has been removedby distillation, 750 grams dry weight of Norwegian marble are added,having a grain size such that 75% of the particles are of a diameterless than 1 μm as measured by the Sedigraph 5100.

Once the co-structure has formed between the grains of talc and marbleafter 30 minutes of agitation, 7 grams by dry weight of a dispersingagent, namely a polyacrylic acid with a specific viscosity of 0.53, areadded to obtain an aqueous suspension of the composite compound of theinvention having a concentration of dry substance equal to 36.6%.

Test N^(o) 54:

This test, illustrating the invention, using the same method and thesame equipment as the preceding test, is conducted with 250 grams dryweight of Finnish talc of a grain size such that 45% of the particlesare of a diameter of less than 2 μm as measured on the Sedigraph 5100,12.5 grams dry weight of a mixture of monomers comprising 80% by weightof acrylic acid and 20% by weight of tristyrylphenol methacrylate with25 moles of ethylene oxide, 115 grams of isopropanol as well as thequantity of water needed to make up an aqueous composition with a 30%concentration of dry substance.

After 30 minutes of agitation, the mixture of monomers is polymerised,using known processes of radical polymerisation in a hydro-alcoholicmedium.

Once the polymerisation is complete and the isopropanol has been removedby distillation, 750 grams dry weight of Norwegian marble are added,having a grain size such that 75% of the particles are of a diameterless than 1 μm as measured by the Sedigraph 5100.

Once the co-structure has formed between the grains of talc and marbleafter 30 minutes of agitation, 7 grams by dry weight of a dispersingagent, namely a polyacrylic acid with a specific viscosity of 0.53, areadded to obtain an aqueous suspension of the composite compound of theinvention having a concentration of dry substance equal to 36.6%.

Test N^(o) 55:

This test, illustrating the invention, using the same method and thesame equipment as the preceding test, is conducted with 250 grams dryweight of a Finnish talc of a grain size such that 45% of the particlesare of a diameter of less than 2 μm as measured on the Sedigraph 5100, 5grams dry weight of stearyl methacrylate, 115 grams of isopropanol aswell as the quantity of water needed to make up an aqueous compositionwith a 30% concentration of dry substance.

After 30 minutes of agitation, the monomer is polymerised, using knownprocesses of radical polymerisation in a hydro-alcoholic medium.

Once the polymerisation is complete and the isopropanol has been removedby distillation, 750 grams dry weight of Norwegian marble are added,having a grain size such that 75% of the particles are of a diameterless than 1 μm as measured by the Sedigraph 5100.

Once the co-structure has formed between the grains of talc and marbleafter 30 minutes of agitation, 7 grams by dry weight of a dispersingagent, namely a polyacrylic acid with a specific viscosity of 0.53, areadded to obtain an aqueous suspension of the composite compound of theinvention having a concentration of dry substance equal to 36.7%.

Example 6

This example is intended to demonstrate the formation of theco-structure or co-adsorption by measuring and comparing the homogeneityof the different suspensions of composite compounds obtained by dilutingto a 20% concentration of dry substance.

To this end, the various aqueous suspensions of the composite compoundsproposed by the invention and the suspensions of the prior art arediluted to a 20% concentration. Their macroscopic cohesion is measuredusing the homogeneity test consisting in determining the content of dryfiller having at least one hydrophilic site at two separate points ofthe suspension representative of the test, namely a point located at thebase of the flask and a point located on the surface of the flask afterdrying the suspension in an oven.

Once dry, the calcium ion content of each sample is determined afterdissolving in HC1 using EDTA sequestering techniques at a pH of 12 andwith a coloured indicator, Eriochrome® Black T.

Test N^(o) 56:

For this test, illustrating the prior art, the aqueous suspension of themixture described in test N^(o) 1 is used.

Test N^(o) 57:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 47 is used.

Test N^(o) 58:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 43 is used.

Test N^(o) 59:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 44 is used.

Test N^(o) 60:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 45 is used.

Test N^(o) 61:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 46 is used.

Test N^(o) 62:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 48 is used.

Test N^(o) 63:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 49 is used

Test N^(o) 64:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 50 is used.

Test N^(o) 65:

For this test, illustrating the invention, the aqueous suspensiondescribed in test No 51 is used.

Test N^(o) 66:

For this test, illustrating the prior art, the aqueous suspensiondescribed in test N^(o) 11 is used.

Test N^(o) 67:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 12 is used.

Test N^(o) 68:

For this test, illustrating the prior art, the aqueous suspension of themixture described in test N^(o) 13 is used.

Test N^(o) 69:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 14 is used.

Test N^(o) 70:

For this test, illustrating the prior art, the aqueous suspensiondescribed in test N^(o) 15 is used.

Test N^(o) 71:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 16 is used.

Test N^(o) 72:

For this test, illustrating the prior art, the aqueous suspensiondescribed in test N^(o) 17 is used.

Test N^(o) 73:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 18 is used.

Test N^(o) 74:

For this test, illustrating the prior art, the aqueous suspensiondescribed in test N^(o) 19 is used.

Test N^(o) 75:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 20 is used.

Test N^(o) 76:

For this test, illustrating the prior art, the aqueous s suspensiondescribed in test N^(o) 42 is used.

Test N^(o) 77:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 41 is used.

Test N^(o) 78:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 29 is used.

Test N^(o) 79:

For this test, illustrating the prior art, the aqueous suspensiondescribed in test N^(o) 30 is used.

Test N^(o) 80:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 52 is used.

Test N^(o) 81:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 53 is used.

Test N^(o) 82:

For this test, illustrating the invention, the aqueous suspensiondescribed in test N^(o) 54 is used

Test N^(o) 83:

For this test, illustrating the invention, the aqueous suspensiondescribed in test No 55 is used.

Test N^(o) 84:

For this test, illustrating the prior art, the aqueous suspensiondescribed in test N^(o) 23 is used.

It should be pointed out that in this test, the method used to measurethe macroscopic homogeneity of the suspension is different from that ofthe preceding tests. In effect, the quantities are not metered bysequestering techniques but by RFA analysis, which involves taking 0.2 gof the dry sample which is mixed with 1.625 g of lithium tetraborate,which is heated to melting temperature to obtain a disc, which is placedin a XRF 9400 machine made by ARL (Switzerland) to determine theelements by readings of the oxides present and then calculating thekaolin present.

The results of all the experiments are set out in Table 1 below. TABLE 1HOMOGENEITY % CaCO₃ at the surface TEST N° % CaCo₃ at the base Prior art56 93.4 - 14.9 Invention 57 72.5 - 74.8 Invention 58 73.0 - 75.5Invention 59 73.7 - 73.7 Invention 60 73.4 - 73.9 Invention 61 73.9 -73.2 Invention 62 74.9 - 76.6 Invention 63 75.7 - 75.2 Invention 6475.3 - 74.5 Invention 65 73.9 - 73.8 Prior art 66 74.7 - 63.9 Invention67 74.4 - 73.4 Prior art 68 88.9 - 25.4 Invention 69 73.2 - 72.5 Priorart 70 90.2 - 37.1 Invention 71 83.1 - 83.5 Prior art 72 45.2 - 89.1Invention 73 85.0 - 82.1 Prior art 74 29.6 - 85.5 Invention 75 81.7 -80.5 Prior art 76 33.6 - 54.6 Invention 77 49.6 - 49.6 Invention 7868.8 - 69.2 Prior art 79 91.9 - 32.5 Invention 80 74.8 - 74.1 Invention81 74.6 - 73.6 Invention 82 74.4 - 75.4 Invention 83 70.3 - 72.7 Priorart 84 23.0 - 2.0**% kaolin at the surface - % kaolin at the base

Table I demonstrates that the aqueous suspensions containing theco-structured composite compounds of the invention have a morehomogeneous content of fillers with at least one hydrophilic site atdifferent points than those containing the standard mixtures of theprior art.

Example 7

This example demonstrates the formation of the co-structure orco-adsorption by measuring and comparing the viscosity and homogeneityof different paper coating colors produced.

To this end, the coating colors are prepared (tests 85 to 94) by mixingin water the composite compounds of fillers or pigments to be testedwith 100 parts of compound to be tested at 65% of dry substance

-   12.5 parts of a carboxylated styrene-butadiene latex sold under the    name of DL950 by Dow Chemical    and a quantity of water needed to obtain a 40% content of dry    substances for tests N^(o) 85 to 92 and a content of dry substance    in the order of 20% for tests N^(o) 93 and 94.

The Brookfield viscosities of the coating colors prepared in this mannerare then measured at ambient temperature at 20 revolutions/minute and100 revolutions per minute using a Brookfield viscometer of the DVIItype fitted with an appropriate spindle.

They are then tested for homogeneity using the same operating method asthat described for the preceding example.

Test N^(o) 85:

For this test, illustrating a coating color of the invention, theaqueous suspension of the composite compound of test N^(o) 2 is used.

Test N^(o) 86:

For this test, illustrating a coating color of the prior art, theaqueous suspension of the mixture of test N^(o) 1 is used.

Test N^(o) 87:

For this test, illustrating a coating color of the invention, theaqueous suspension of the composite compound of test N^(o) 4 is used.

Test N^(o) 88:

For this test, illustrating a coating color of the prior art, theaqueous suspension of the mixture of test N^(o) 3 is used.

Test N^(o) 89:

For this test, illustrating a coating color of the invention, theaqueous suspension of the composite compound of test N^(o) 6 is used.

Test N^(o) 90:

For this test, illustrating a coating color of the prior art, theaqueous suspension of the mixture of test N^(o) 5 is used.

Test N^(o) 91:

For this test, illustrating a coating color of the invention, theaqueous suspension of the composite compound of test N^(o) 8 is used.

Test N^(o) 92:

For this test, illustrating a coating color of the prior art, theaqueous suspension of the mixture of test N^(o) 7 is used.

Test N^(o) 93:

For this test, illustrating a coating color of the invention, theaqueous suspension of the composite compound of test N^(o) 10 is used.

Test N^(o) 94:

For this test, illustrating a coating color of the prior art, theaqueous suspension of the mixture of test N^(o) 9 is used.

The results of all the experiments are set out in Table 2, theconsistency of the coating colors of each of the tests being determinedby introducing a spatula containing said coating colors. TABLE 2HOMOGENEITY VISCOS- VISCOS- % CaCO₃ ITY in ITY in at surface TES mPa · smPa · s CONSIS- CaCO₃ N° (20 r/mn) (100 r/mn) TENCY at the baseInvention 85 190 66 Soft 63.5-63.1 Prior art 86 14 24 Hard 76.1-34.8Invention 87 765 180 Soft 62.6-63.0 Prior art 88 110 60 Medium 75.5-22.3hard Invention 89 75 50 Soft 61.2-64.1 Prior art 90 16 29 Hard 65.8-48.5Invention 91 242 88 Soft 64.1-64.4 Prior art 92 18 20 Hard 68.0-23.0Invention 93 885 217 Soft 62.6-63.3 Prior art 94 55 47 Medium 66.4-50.5hard

Table 2 demonstrates that the coating colors of the invention containingthe aqueous suspensions of co-structured composite compounds proposed bythe invention are soft in appearance and have a higher Brookfieldviscosity than that of the standard comparative mixtures of the priorart, thereby illustrating the co-structuring of the fillers or pigments.It is also clear that they have a more homogeneous content of fillershaving at least one hydrophilic site at different points of the coatingcolors than that contained in the standard mixtures of the prior art.

Example 8

This example relates to the measurements taken on the rheologicalbehaviour of different aqueous compounds prepared in accordance with themethod used in example 1.

The rheological behaviour of the different aqueous suspensions preparedin the same way as that used for example 1 is measured forviscoelasticity at 20° C. using a Stress Tech® device by ReologicaInstruments AB (Sweden) fitted with CC25 coaxial cylinders.

The same method was used to measure the rheological behaviour of thesuspension produced in each of the tests, namely a sample of thesuspension to be tested is injected into the cylinder of theviscoelasticity-measuring device and is pre-stressed at 10 Pa for 12seconds and, after a waiting time of 180 seconds, stress is applied at alinear progression from 0.025 Pa to 20 Pa in 100 seconds and 40intervals.

The yield stress, corresponding to the stress applied to the suspensionto break the internal bonds and obtain a suspension of a reducedviscosity is determined by the maximum value of the viscosity curve inPa·s as a function of the stress in Pa.

Test N^(o) 95:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 2 is used.

Test N^(o) 96:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 1 is used.

Test N^(o) 97:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 4 is used.

Test N^(o) 98:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 3 is used.

Test N^(o) 99:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 6 is used.

Test N^(o) 100:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 5 is used.

Test N^(o) 101:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 8 is used.

Test N^(o) 102:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 7 is used.

Test N^(o) 103:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 10 is used.

Test N^(o) 104:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 9 is used.

Test N^(o) 105:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 12 is used.

Test N^(o) 106:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 11 is used.

Test N^(o) 107:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 14 is used.

Test N^(o) 108:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 13 is used.

Test N^(o) 109:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 15 is used.

Test N^(o) 110:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 16 is used.

Test N^(o) 111:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 17 is used.

Test N^(o) 112:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 18 is used.

Test N^(o) 113:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 41 is used.

Test N^(o) 114:

For this test, illustrating the prior art, the aqueous suspension of themixture of test N^(o) 42 is used.

Test N^(o) 115:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 52 is used.

Test N^(o) 116:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 53 is used.

Test N^(o) 117:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 54 is used.

Test N^(o) 118:

For this test, illustrating the invention, the aqueous suspension of thecomposite compound of test N^(o) 55 is used.

The results of all the experiments are set out in Table 3 below: TABLE 3VISCOSITY YIELD STRESS TEST N° in Pa · s in Pa Invention 95 642 3.072Prior art 96    6.90 0.04465 Invention 97 164 0.9573 Prior art 98   1.49 0.03728 Invention 99 14 700   8.141 Prior art 100    0.5270.03056 Invention 101 235 0.5842 Prior art 102    3.07 0.02965 Invention103 1330  1.708 Prior art 104   38.4 0.3594 Invention 105 286 0.709Prior art 106   12.32 0.079 Invention 107 2157  4.824 Prior art 108   4.81 0.102 Prior art 109    1.56 0.047 Invention 110  92 0.445 Priorart 111   43.2 0.099 Invention 112 589 0.336 Invention 113 938 1.580Prior art 114   40.6 0.185 Invention 115 222 0.395 Invention 116   8.60.149 Invention 117 339 0.741 Invention 118   9.1 0.198

Table 3 demonstrates that the aqueous suspensions of the co-structuredcomposite compound of the invention have a higher yield stress than thatof the standard comparative mixtures of the prior art, characteristic ofsuspensions exhibiting good stability.

Example 9

This example demonstrates the quality of the printability of thedifferent paper coating colors produced in example 7.

This printability test, known as ISIT (Ink Surface Interaction Test) isbased on a printing machine fitted with a device for creating andmeasuring the force needed to separate a contact disk from a film ofprinting ink. This machine consists on the one hand of the device whichcreates and measures the force and on the other an inking disk whichrotates above the sheet of paper to be tested and is sold under the nameof <<Ink Surface Interaction Tester>> by SeGan Ltd.

To this end, the different sheets of paper to be tested are prepared byapplying the various coating colors to be tested on these sheets ofpaper using the Erichsen Model 624 laboratory coater made by ErichsenGmbH & Co. KG (Germany) fitted with detachable rotating blade coaters.

Once it has been coated with 7.5 g/m², the paper to be tested is fixedon a roll fitted with a two-sided adhesive tape. An offset ink isapplied by placing the inking disk in contact with a width of 25 mm asit is rotated 180°. The printing speed and pressure are adjustable andare in the order of 0.5 m/s and 50 kg respectively. The volume of ink isunder standard conditions of 0.3 cm³ thus applying a thickness ofapproximately 1 g/m² to the sheet of paper to be tested.

The printing process is followed by a series of measurements todetermine the tack force repeated at pre-selected time intervalsdepending on the time taken to separate the tack disk (of the samedimensions as the printing disk) from the film of ink.

A coating of offset-print quality nitrile rubber is usually used for thetack disk but any equivalent material may be used.

The contact force between the tack disk and the ink is measured by asystem which generates an electromagnetic force. The amplitude andduration of the contact force are adjusted until a uniform adhesion isreached between the surface of the film and the tack disk at the end of3 seconds. Rotating the sheet of paper slightly whilst theelectromagnetic force is applied will ensure a close contact andcontinuity of the film of ink. Once the magnetic force is stopped, thetack disk is pulled back from the printed film by the force of a tensedspring, this force being sufficient to separate the disk from the filmof ink. A strain gauge, mounted between the tack disk and the spring,generates a signal which is recorded as the tack force.

The sequence is automatically repeated for 13 cycles.

On the first and the thirteenth cycles, the printing densities aremeasured using a Gretag D 186 densitometer.

This operating method is used for each of the coating colors to betested, as follows:

Test N^(o) 119:

Illustrating the invention, the coating color of test N^(o) 85 is used.

Test N^(o) 120:

Illustrating the prior art, the coating color of test N^(o) 86 is used.

Test N^(o) 121:

Illustrating the invention, the coating color of test N^(o) 87 is used.

Test N^(o) 122:

Illustrating the prior art, the coating color of test N^(o) 88 is used.

Test N^(o) 123:

Illustrating the invention, the coating color of test N^(o) 89 is used.

Test N^(o) 124:

Illustrating the prior art, the coating color of test N^(o) 90 is used.

Test N^(o) 125:

Illustrating the invention, the coating color of test N^(o) 91 is used.

Test N^(o) 126:

Illustrating the prior art, the coating color of test N^(o) 92 is used.

Test N^(o) 127:

Illustrating the invention, the coating color of test N^(o) 93 is used.

Test N^(o) 128:

Illustrating the prior art, the coating color of test N^(o) 94 is used.

The results of all the experiments are set out in Tables 4 and 5 belowand graphs 1 to 5 appended to this application.

Table 4 contains the results showing values of the tack force as afunction of time whilst Table 5 gives the values of the printing densityfor tests 119 to 122.

Graphs 1 to 5 show the force which has to be applied to separate thedisk from the film after printing as a function of time and can beinterpreted taking the following three phases into account:

(i) the rise time,

-   -   which essentially relates to the absorption and penetration        speed of the ink as it makes initial contact with the surface to        be printed.    -   The microporosity and wettability of this surface are major        factors in terms of the rise time of this force.    -   The longer the rise time to the maximum value of the force, the        more efficiently the binder of the ink is absorbed, the less the        film of ink will be susceptible to splitting and the better the        adhesion between the ink and the paper, thus producing a better        result.        (ii) The maximum value of the tack force,    -   which measures on the one hand the adhesion of the layer of ink        which is immobilised on contact, the printing substrate and, on        the other hand, the cohesion with the ink contained on the        surface of the substrate. Consequently, the higher this maximum        value of tack force for a constant cohesion, the better the        adhesion will be and the better the print will be.        (iii) The fall time of the force,    -   which represents the drying of the ink.

The slower this fall time, the slower the ink will dry, the lesslikelihood there will be of splitting in the structure of the ink andthe better the print will be. TABLE 4 Test 119 Test 120 Test 121 Test122 Test 123 Test 124 Test 125 Test 126 Test 127 Test 128 InventionPrior art Invention Prior art Invention Prior art Invention Prior artInvention Prior art Time: 5 Force: Force: Force: Force: Force: Force:Force: Force: Force: Force: seconds 1.59 3.93 2.73 3.74 3.94 4.32 2.822.70 3.29 4.67 Time: 15 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 5.22 6.39 5.52 5.98 6.61 5.34 5.08 4.996.60 6.55 Time: 26 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 6.71 6.11 6.46 5.89 6.77 5.27 6.30 5.397.38 6.08 Time: 37 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 7.19 5.68 6.85 5.52 6.36 4.84 6.37 5.287.22 5.30 Time: 57 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 7.21 5.45 6.84 5.50 5.63 4.63 6.10 4.636.1° 3.74 Time: 78 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 6.77 4.61 6.64 4.88 5.44 3.89 5.46 3.045.00 3.07 Time: 98 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 6.06 4.41 6.37 4.71 4.56 2.95 5.05 2.734.00 2.10 Time: 139 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 5.34 3.25 5.38 4.30 3.51 2.42 4.16 1.653.25 1.25 Time: 179 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 5.07 2.27 4.66 3.04 2.59 2.09 3.15 0.931.73 0.79 Time: 220 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 4.54 1.67 3.80 2.22 2.37 1.57 2.78 1.391.36 0.72 Time: 281 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 3.67 1.02 3.22 1.42 2.03 0.99 2.24 1.321.16 0.64 Time: 341 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 3.12 0.88 2.67 1.01 1.21 0.90 1.55 1.190.71 0.59 Time: 402 Force: Force: Force: Force: Force: Force: Force:Force: Force: Force: seconds 3.23 0.92 2.43 0.86 1.30 0.89 1.56 1.070.72 0.66

TABLE 5 Print density Print density Test N° 1st cycle 13th cycleInvention 119 1.58 1.05 Prior art 120 1.49 0.97 Invention 121 1.52 1.05Prior art 122 1.48 0.94

Table 4 and graphs N^(o) 1 to 5 demonstrate that the coating colorsproposed by the invention have slower rise and fall times and highertack force values, which means that they exhibit better printability interms of adhesion, brightness and print yield.

Table 5 demonstrates that the coating colors of the invention havehigher print densities than those of the comparative coating colorsknown from the prior art.

Example 10

This example relates to the opacity measurement and more specifically todetermining the light scattering coefficient S of the various coatingcolors.

The method used to determine the light coefficient S, well known tothose skilled in the art, is as follows:

For each test, a sheet of paper containing no wood is coated with thecoating color to be tested.

Before being coated and prior to each test, this sheet of paper, thedimensions of which are 10 cm×6 cm and with a specific weight of 75.5g/m², is weighed and then irradiated with light of a wavelength equal to457 nm on a black plate using an Elrepho 2000 spectrophotometer byDatacolor (Switzerland) to determine the base reflection index R_(b).

Each of the coating colors to be tested is then applied to thispre-weighed sheet of paper with a laboratory coater fitted withdetachable rotating coating blades sold as reference model 624 byErichsen (Germany). Each sheet of paper coated in this manner at 7.5g/m² is then irradiated with light of a wavelength equal to 457 nm bymeans of an Elrepho 2000 spectrophotometer by Datacolor (Switzerland) ona black plate to determine the reflection index R₀ and on a stack ofsheets of paper which have not been coated in order to determine thereflection index R₁, where r is the reflection index of the stack ofuncoated sheets of paper.

The reflection index R_(SC) of the single coat, on a black background,is then determined using the formula:$R_{sc} = \frac{{R_{1} \cdot R_{b}} - {R_{0} \cdot r}}{{{( {r_{1} - R_{0}} ) \cdot r}\quad R_{0}} + R_{b} - r}$and the transmittance T_(SC) of the coating$T_{sc}^{2} = \frac{( {R_{0} - R_{sc}} )( {1 - {R_{sc}R_{b}}} )}{R_{b}}$to obtain a theoretic reflection value R_ for a coating of infinitethickness given by the formula:$\frac{1 - T_{sc}^{2} + R_{sc}^{2}}{R_{sc}} = \frac{1 + R_{\quad -}^{2}}{R_{-}}$The scattering coefficient S characteristic of the opacity can becalculated from this formula, knowing that, for a coating weight P,$\begin{matrix}{{S.P.} = {\frac{1}{b}\coth^{- 1}\frac{( {1 - {a\quad R_{sc}}} )}{b\quad R_{sc}}}} \\{a = {0.5\quad( {\frac{1}{R_{-}} + R_{-}} )}} \\{where} \\{b = {0.5\quad( {\frac{1}{R_{-}} + R_{-}} )}}\end{matrix}$

Test N^(o) 129:

For this test, illustrating the prior art, the coating color of testN^(o) 86 is used.

Test N^(o) 130:

For this test, illustrating the invention, the coating color of testN^(o) 85 is used.

Test N^(o) 131:

For this test, illustrating the prior art, the coating color of testN^(o) 88 is used.

Test N^(o) 132:

For this test, illustrating the invention, the coating color of testN^(o) 87 is used.

All the results are set out in Table 6 below: TABLE 6 PRIOR PRIOR ARTINVENTION ART INVENTION TEST N° 129 130 131 132 S in m²/kg 143 157 104136

Table 6 demonstrates that the coating colors of the invention have ahigher light scattering coefficient S than the comparative coatingcolors of the prior art.

Example 11

This example relates to the direct opacity measurement and the whitenessof the coating colors in compliance with the TAPPI T452 ISO 2470standard.

For each test, a sheet of paper containing no wood and of dimensions 10cm×6 cm, having a specific weight of 75.5 g/m², is coated with thecoating color to be tested using a laboratory coating machine withremovable rotating blade coaters, marketed as Model 624 by Erichsen(Germany).

Each sheet of paper coated in this manner with 7.5 g/m² is then exposedto light of a wavelength of 457 nm using an Elrepho 2000spectrophotometer by Data Color (Switzerland) to determine the opacityand whiteness.

This example also relates to the brightness measurement. The brightnessmeasurement is taken on the same coated sheets of paper as those used totake the direct opacity and whiteness measurements.

This method involves feeding the coated sheet of paper into thelaboratory brightness meter, LGDL-05/2 Lehmann Messtechnik AG,Switzerland) which measures the 75° TAPPI brightness according toLehmann.

Test N^(o) 133:

For this test, illustrating the prior art, the coating color of testN^(o) 88 is used.

Test N^(o) 134:

For this test, illustrating the invention, the coating color of testN^(o) 087 is used.

Test N^(o) 135:

For this test, illustrating the prior art, the coating color of testN^(o) 92 is used.

Test N^(o) 136:

For this test, illustrating the invention, the coating color of testN^(o) 91 is used.

Test N^(o) 137:

For this test, illustrating the prior art, the coating color of testN^(o) 94 is used.

Test N^(o) 138:

For this test, illustrating the invention, the coating color of testN^(o) 93 is used.

The results of the opacity measurement experiments are set out in Table7 below: TABLE 7 PRIOR ART INVENTION TEST N° 133 134 OPACITY 91.1% 92.2%

The results of the whiteness measurement experiments are set out inTable 8 below: TABLE 8 PRIOR ART INVENTION TEST N° 135 136 WHITENESS84.8% 87.6%

The results of the brightness measurement experiments are set out inTable 9 below: TABLE 9 PRIOR ART INVENTION TEST N° 137 138 BRIGHTNESS41.4% 48.6%

Tables 7 to 9 demonstrate that the coating colors of the invention havea higher opacity, whiteness and brightness than those produced by thecomparative coating colors of the prior art.

Example 12

This example relates to the opacity measurement conforming to the DIN53146 standard and the whiteness of sheets of paper containing, in themass, the uncoated filling compounds proposed by the invention andcomparisons of these with those containing the standard suspensions ofmixtures of the prior art.

To this end, sheets of paper are made from a cellulose pulp of SR 23degree containing a woodless sulphate paste and fibres comprising 80%birch and 20% pine. 45 g dry weight of this pulp are then diluted in 10litres of water in the presence of about 15 g dry weight of the fillercomposition to be tested to produce experimentally a filler content of20%. After 15 minutes of agitation and adding 0.06% by dry weight,relative to the dry weight of paper, a retention agent of thepolyacrylamide type, a sheet is made with a grammage equal to 75 g/m²and filled to 20%. The device used to make the sheet is a Rapid-Köthen20.12 MC model by Haage.

The sheets prepared in this manner are dried for 400 seconds at 92° C.and in a vacuum of 940 mbar. The filler content is controlled byanalysing the ashes.

The different values for opacity and whiteness are then determined usingthe same method as before.

The following tests were conducted.

Test N^(o) 139:

For this test, illustrating the prior art, the mixture of test N^(o) 1is used.

Test N^(o) 140:

For this test, illustrating the invention, the composite compound oftest N^(o) 2 is used.

Test N^(o) 141:

For this test, illustrating the prior art, the mixture of test N^(o) 3is used.

Test N^(o) 142:

For this test, illustrating the invention, the composite compound oftest N^(o) 4 is used.

The results of the whiteness measurement experiments are set out inTable 10 below: TABLE 10 PRIOR ART INVENTION TEST N° 139 140 WHITENESS86.9 87.7

The results of the opacity measurement experiments are set out in Table11 below: TABLE 11 PRIOR ART INVENTION TEST N° 141 142 OPACITY 88.7 90.3

Tables 10 and 11 demonstrate that the sheets filled with theco-structured composite compounds of the invention have a higher opacityand whiteness than those filled with the standard mixtures of the priorart.

Example 13

This example relates to the opacity measurement and more specifically todetermining the light scattering coefficient S of an aqueous paintcomposition containing, essentially water and 100 parts of the compositecompound to be tested with a 65% dry content as well as 9-8 parts of abinder polymeric dispersion of the styrene-acrylic type.

This coefficient is measured by using the same way that used for example10, except that the support to be coated is not a sheet of paper but analuminum sheet.

The obtained results are completely the sames as those obtained in thetests No. 129 and No. 130, and so demonstrate that the paintcompositions according to the invention have a higher light scattering Scoefficient than a paint composition of the prior art and so anincreased opacity.

From the results of the example 10, the skilled man in the art wasexpecting the results of the example 13.

In fact, this S coefficient, as confirmed by the disclosed calculationin the example 10, is independent from the support (paper or metal orcement sheet) and depends only from the coating composition i.e. fromthe paper coating color or from the paint composition.

1. A sheet of base paper to be coated, which contains an uncoatedfilling composition which contains a composite compound of mineral ororganic fillers or pigments, which is comprised of a) a combination ofat least two mineral or organic fillers or pigments, at least one ofwhich has a surface with at least one hydrophilic site and the other atleast has at least one organophilic site co-structured or co-adsorbed bybeing blended with b) at least one binding agent.
 2. The sheet of basepaper as claimed in claim 1, which has a higher opacity determined inaccordance with the DIN 53146 standard than that of a sheet of papercontaining the standard suspensions of corresponding mixtures.
 3. Thesheet of base paper as claimed in claim 1, which has a higherwhiteness-determined in accordance with the TAPPI T452 ISO 2470 standardthan that of a sheet of paper containing the standard suspensions ofcorresponding mixtures.